Method and article for cleaning oil wells and the like



l.. N. SCHEUERMANN' ETAL METHD- AND ARTICLE FOR CLEANING OIL WELLS ANDTHE LIKE July 4, 1944.

Filed March 22, 1943 Patented July 4, 1944 METHOD AND BTICIE FOBCLEANING OIL WELLS AND THE LIKE Leonhard N. Scheuermann anIlLGabrielPecot,

New Orleans,

Application March 22, 1943', Serial No. 480,078

18 Claims.

The present invention relates to improvements in methods and articlesfor cleaning oil wells and the like, and is a continuation in part ofapplication Serial No. 411,248, filed September 17, 1941, now forfeited.

An object of the invention is to provide a method for cleaning oil wellsand the like in which accumulations of paraffin or other obstruction maybe easily and quickly removed to restore full flow in the well or pipe.`

'I'he improvedmethod is useful in cleaning oil lines, flow lines,gathering lines, separators, measuring and storage tanks and in fact anyline or receptacle that is subject to paraln or other deposit clogging.

Another object of the invention is to utilize a mechanical abradant inentrainment with the oil in the line to thus acquire suilicient momentumto cut the paraflin in a mechanical manner, and in the oil the abradantor abrasive material will be insoluble.

A further object of the invention is to provide an improved method andmaterial for use in cleaning pipe lines and thelike in which, while theabrasive is insoluble in the oil so as to be entrained in the currentthereof for mechanical impingement upon the paramn and the cutting awayof the same, such abrasive will be soluble in water to the end that anyaccumulations resulting from combinations of the parailin and abrasivecan be dissolved out by'circulating water through the well or line. Inaddition to the removing of paraln deposits, the improved method isuseful in cleaning and removing other deposits and/or obstructions inpipe lines and the like.

consolidate such discrete particles into a plug With the foregoing andother objects in view, the invention will be more fully describedhereinafter, and will be more particularly pointed out in the claimsappended hereto.

In the drawing, wherein like symbols refer to like or correspondingparts throughout the several views,

Figure 1 is a vertical sectional view of a conventional form oil oilwell with the invention applied,-

Flgure 2 is a perspective view, with parts broken away and parts shownin section, illustrating a plugconstructed in one form according to theinvention, and Y i Figure 3 is a plan view,'magnifi ed, of a form 'ofsoluble abrasive crystal employed. A In accordance withthe improvedmethod, solid and semi-solid obstruction in oil iiow lines containingoil may be removed by placing in the oil stream discrete particles, andpermitting the flowing oil to entrain such particles and cause them tocontact with the obstruction. Salts' in general may be used as theparticles. Crystalline salts'are particularly effective. 'I'he materialswhich produce most unusual and superior ful salt in view of its generalphysical properties; its solubility in water and insolubility in oil areadditional factors which make common salt a preferred material. Someexamples of other salts useful for the purpose are: 1 l

Cupric sulfate (CuSO4) magnesium sulfate (Epsom salt-MgSOi'IHzO);potassium chloride (KCl); potassium nitrate (KNOa) sodium nitrate(N8/N03).

It is to be understood that these are not all of the salts that can beused =but that theyA are merely given by way of example.

Common salt of thecoarse variety, such,` for instance, as that typecommonly called "icecream salt," has been found to be extremely usefulfor the purpose. Ice-cream salt is common crystalline salt having anapproximately particle size such as to pass through a 4 mesh screen andto be retained 'by a l0 mesh screen. Particularly effective results havebeen obtained by the use oi a 7 to l0 mesh salt. l

The method for cleaning oil wells mayl vary somewhat, dependent upon thecharacter and place of the deposits. The following are only some of theexamplesy practicable according to the improved method.

Example 1.-For cleaning oil lines. we have found that coarse salt, asoluble abrasive, when lowered into the tubing of a well4 and'releasedat given depths,`will, upon rising with the ilow of oil, act asthousands of miniature knives, cutting away the parain and/or otherundesirable deposits that may -be left behind through the flowing ofoil. Deposits of paramn or other ,hydrocarbons are frequently depositedon the walls of the tubing or pipe lines whenv oil is owed therethrough.The type of deposit. hardness, volume of deposition and other factorsare functions oi the type of OiLtemperature, size of pipe, pressure,etc. undesirable deposits into very small particles which are carriedwith the ow of oil up through the choke and then through the manifoldthrough the ilow line into the separator, cleaning everything in itspath. The abrasive is not soluble in the oil and retains its crystallineforml However, it is soluble in water, as hereinafter explained.

Example 2.-"I'he salt or soluble abrasive may be mixed with the oil fromthe well being treated, and then allowing such mixture to drop throughthe lubricator on top of the well. The salt settles by gravity to apoint below the deposit. It is to be noted that the salt or abrasive issoluble in water and insoluble in oil. Thereupon the well is allowed toflow, the same action taking place from this point as explained inExample 1.

Erample 3,-In cleaning oil lines, gathering lines, ow lines, etc., thesoluble abrasive or coarse salt is mixed with the oil from the wellbeing treated. The amount of the abrasive suggested is five pounds percharge. This suggestion is a minimum, and the maximum is recommended inthat parain or oil deposits are harder in some wells than others, thusrequiring more soluble abrasive action to remove the harder deposits. Anapproximate maximum charge of 100 to 125 pounds is recommended in caseswhere the deposit is harder and/or thicker, and thus more dilcult toremove.

Example 4.-'Ihe choke may be removed and the soluble abrasive mixed withoil poured into the riser. Or the choke may remain in the manifold, theriser being broken below the choke and the soluble abrasive-oil mixturepoured into the broken connection or riser.

Example 5.-Insert a T below the choke and use this connection moreorless as a funnel to receive the abrasive mixed with oil. After themixture has been introduced, a bull plug may be inserted in the openingand the well opened, allowing the abrasive action to occur in the linefrom the point where the soluble abrasive has been introduced. The abovemethod will prove most satisfactory when working with wells underpressure. The pressure from the well will agitate the soluble abrasive,thereby creating the desirable mechanical action. In wells that lackpressure, such as pumpers, the pressure may be obtained through the useof air pressure pumps or oil .pressure pumps to create the abrasiveaction necessary.

Eixample 6.-In cleaning tanks, gas, air or Azu Such soluble abrasivecuts the agitation which is necessary to'put the soluble.-

abrasive into action. It is suggested that in open tanks the abrasive bescattered over the top of` the undesirable deposits. The gas pressurefrom wells, or air pressure created by an air pressure pump, or steampressure should be used to agltate the soluble abrasive in order thatsaid undesirable deposits may be so cut that removing will be easilyaccomplished.

The result obtained by practicing methods according lto the aboveexamples has been found most satisfactory in practice. Wells, now lines,etc., have been caused to return the allowable oil production to normal.all obstructions hindering the flowing of oil being removed with thesoluble abrasive.

Sand has been heretofore proposed as an abrasive, but from a comparativestandpoint sand is impractical as well as dangerous when introduced inthe wells, flow or pipe lines.

Sand has a, deiinite tendency to adhere to paraffin and to agglomeratewith the accumulations and deposits of paraiiin or other foreignmatters, thus clogging the tubing or lines and making the iiow of oilmore difiicult because the diameter of the hole through which the oiliiows is consequently made smaller instead of larger as with coarsesalt. In the event coarse salt would for some unknown reason clog theline or the tubing, the remedy would be to ilush the line with water,thus dissolving the obstructions. The dissolving action will be throughthe solution of the salt agglomerated with the deposit and theentrainment of the loosened deposit. Sand would be'impossible todissolve under the same conditions. When sand is used for any type ofcleaning, expensive equipment is needed. Sand, when used as an abrasive,must be shot from a mechanical device of some sort in order v,

to obtain the desired results. Coarse salt is very inexpensive, but atthe same time it is the most eilcient parailn remover.

From experience we have learned that a soluble abrasive such as coarsesalt has none of the disadvantages of sand. To an oil operator, sand isthe antithesis of a cleaning agent, and no oil operator could beprevailed upon to risk the hazards of the use of sand for cleaningpurposes.

steam pressure may be employed to bring about It will be understood thatthe steps of the method might be used in other order than thatv set out,and we do not wish to be limited except as required by the claims.

Referring more particularly to the drawing, il designates the tubing ofan oil well, up throughwhich moves the oil from the oil-bearing stratumil, and I2 represents a deposit of paraffin, asphalt, carbonaceousdeposit or the like which tends to clog the passage and restrict, and inels and cooler strata, a temperature point is.

reached where these constituents are deposited on the walls of thetubing. Small original accretions grow and form nuclei about which i'ormfurther deposits. The problem is to dislodge and remove suchaccumulations. To this end particles or crystals i3 (Figure 3) ofice-cream salt, or other soluble abrasive, are introduced in gangquantities Il (Figure 1) to a point below the deposit i2 by means ofplugs I5 (Figure 2) dropped down through the tubing i0 in successivephases or doses as indicated at i5, lib and i5 (Figure 1). A funnelpiece i6 may be used `crystals Il.

asnseaao -to icharge the plugs I into the head of the tubing, theliberation of a plug being controlledv to use from climatic moisture andto assist in the movement of the plug through the line, prior todisintegration. The plug will remain hard and cohesive until passingbelow the deposit I?,

' to remain shut-in after the introduction of the where it willdisintegrate into the myriad'off These crystals, as seen in Figure 3,are relatively large and have irregular and jagged edges I3 for cuttingand slicing the deposits I2.

In use, the plugs I5 in suitable numbers are introduced into the wellthrough its surface connections and allowed to fall through the tubingwhile the well is shut-in. By virtue of the shape and weight of theplug, it will rapidly descend past the point I2 and below the depth ofthe accumulation. The plugsl, as shown in Figure 2, are preferablypointed and cylindrical in shape land of such diameter as to permit freepassage The plug is so constructed that the various physical factorspresent below the depth of the l parainic or asphaltic accumulation willcause its disintegration and the subsequent release of the loosecrystals. The disintegration of the plug form is further advanced-byother physical. factors which have their effect during the fall of theplug from the surface to the-desired point of disintegration and theplug is constructed and arranged to take advantage of these factors`which are. namely: (1)' heat, (2) pressure, and (3) vibration andagitation created by the flow of oil.

(1) Heat-.When the plug becomes heated in the oil well, the paraiincoating melts and the binder is dissolved in the warm,1 oil, thuscausing the plug to disintegrate, allowing the discrete particles toslice and cut away the undesirable deposits while entrainingin the oil.

(2) Pressure-The paraffin coating cracks or breaks up upon applicationof pressure. allowing the oil to come in contact with the oil solublebinder, thus releasing the salt crystals, the oil making the bindernon-cohesive.

(3) Vibration and agitation- When loil is owving through the well orline, enough vibration leasing the salt crystals so that the discreteparticles will cut or slice away vthe undesirable deposits whileentrained in the oil flow.

The depth ofV parailinic or asphaltic accumulations within weil tubingis largely controlled byI the melting -point ofthe accumulationsand theL "geothermal gradient. `The geothermal gradient varies, as does themelting pointl of the accumulations. Therefore, the `plug shouldv bedesigned for a speciflcfeld, ywhere necessary, or a certain type plugmay be used within various ranges of on the geothermal gradient andmelting point of the coating on the plug.

Thus, through the use of the plug form, it is possible to place loose.soluble abrasive crystals below the depth of accumulation.' The rate offall of the plug through the particular oil, based largely von specificgravityand viscosity, determines the length of time that the well is'allowed plug at the surface. After this predetermined period, which iscalculated to allow the plug to fall '.a sufficient distance below thedepth of accumulation, the Well is re-opened and the loose solubleabrasive crystals are then entrained in the flow of oil and cut andremove the accumulation within the tubing. The use of the plug is by nomeans coniined to its usage within tubing, but the plug has beenprimarily designed for use within tubing to allow the placement of thesoluble abrasive crystals at a point below the depth of theaccumulation. The use of the plug for the removal of the'paralnic andasphaltic accumulations in surface ow lines is abetted `by the followingfactors: 1j, ease of handling; 2, less waste of material; 3. fasterapplication; and@ less man power to apply;

The plug is constructed by mixing the soluble abrasive crystals with abinder which is\ soluble in oil. shaped in a mold and subjected to adryingand final formation process. After the plug has been thoroughlydried, it is removed from the mold or other forming equipment and coatedwith parafn IB or other substance having a melting point closelyrelating to that of the accumulation with: in the line to be cleaned.Upon being introduced into the tubing or line, the various forces ofpressure, heat and agitation cause the saturation of theplug with oil;disintegration takes place and thus the crystals are released in a looseform.

The length and diameter of the plug are determined by the size of theline or tubing to be cleaned. Its length is determined primarily by theamount of material necessary for removal of the accumulation, butlimited in its length to ease of handling, formation and shipment. Inthe event that a larger volume of material is required than can be`contained in a single plug. the cleantum when entrained in loose formwith the rapy idly moving oil stream flowing upwardly toward lthesurface, by which such particles are caused to'collide with the depositI2 with sufficient velocity and momentum to cut and slice it away. ThisAmechanica1 action chips, cuts, slices and by attrition wears thedeposit, reduces it and nally removes .such deposit.

This is ,the` action of the particles. L

A furtherjstep of the method, `which 'maybe practiced in those caseswhere the depositvis refractory by reason of agglomeration with the saltpa'rticleais to circulate water. or some other suitable solventthroughthe tubing or'to the agglomerated deposit after the initial action ofthe'salt. The water will dissolve the salt as it exsts asa structuraland coherent part of obstructive accumulations in the line, thusvhollow- The mixture is then formed into a plug,-

By reason ing out and destroying the foundations and honeycomning theseaccumulations or obstructions so the passage of the oil through theskeletonize'd structure will be able to wear it down and entrainv it forremoval from the oil well.` Thus, the salt crystalshave a doublefunction of hardhitting mechanical action and attrition, and also thepower under solvent treatment to dissolve and disappear from obstructionmasses to break and weaken those masses from within.

The physical form of ice-cream or coarse salt crystals cooperates withthe action of entrainment in a vehicle such as oil to the end ofbringing about the attrition of crystals I3 against the deposit i2. Theresult is to restore improved iiow in the well or pipe. y

The improved method and article will be found useful in removing paralnaccumulations or such other obstructions as pipe scale of various types.The action of the crystals is particularly applicable to hydrocarbonaccumulations, such as parailin, asphalt, gums, etc.

Paramn may be used as a binder or as a coating for the plug. As acoating it acts as preservation agent to protect the plug from theelements, handling conditions, etc. The parailln also acts as alubricant while the plug is traveling through the line, and mostparticularly as such when traveling vertically downward through tubing.

The plug form, while useful in horizontal lines,

is primarily designed for and useful in vertical tubing whereby discreteparticles are effectively transported from downstream to upstreamthrough the tube. Thus, the plug is designed to hold the particlestogether and to transport them from downstream to upstream, and thusplace them at an upstream point where they can be entrained in the fluidstream, and then carry out the cleaning process. While we have describeda preferred form of our invention, it will be apparent to those skilledin the art, that there are many modifications thereof which come withinthe scope of our invention, as deilned in the claims.

What is claimed is:

1. The herein described method for cleaning oil lines and the like whichconsists in introducing coarse salt crystals intoa body of oil flowingin the line whereby such crystals are carried along with the body' ofoil and caused thereby to impinge against accumulations of parafiin andthe like to cut and lslice such paraflln by mechanical action.

of water or other solvent for the crystals to dis- 4. The method forremoving solid and semisolid obstruction from oil flow lines containingoil, comprising placing discrete abrasive, water soluble particlesupstream from the obstruction, and flowing the oil containing thediscrete particles in entrained condition through the ilow gratable,discrete, abrasive water soluble, crystalline particles upstream fromthe obstruction.,

disintegrating the plug into discrete particles, and flowing the oilcontaining the discrete particles in entrained condition in contact withthe obstruction at a rate of flow suillcient to remove at least a. partof said obstruction.

9. The method of claim 8 characterized in that the particles are a,salt.

10. The method of claim 8 characterized that t-he particles are sodiumchloride.

11. The method of claim 8 characterized in .that the particles arecoarse, salt crystals.

122 The method for removing solid and semisolidobstruction in verticaloil ow lines containing oil, comprising consolidating into a plugnumerous abrasive water soluble crystalline particles, dropping the plugfrom above the obstruction down past the obstruction to a point belowthe obstruction in the line, disintegrating the plug below theobstruction to liberate the particles,k and flowing the oil containingthe particles in entrained condition in contact with the obstruction ata rate of ilow sufficient to remove at least a part of said obstruction.

13. An article for removing solid and senilsolid obstruction from oil owlines containing oil, comprising numerous abrasive water solublecrystalline particles, and a binder to hold the particles into plugform.

14. An article for removing solid and semisolid obstruction from oilflow lines containing oil, comprising a plug, said plug comprisingdiscrete abrasive water soluble crystalline particles. and a binder tohold the particles into said plug form, said binder being soluble inoil.

15. An article as recited in claim 14 in which the particles are a salt.

16. The article as defined in claim 14 in which the particles arecoarse, salt crystals.

17. The method in accordance with claim 4 in which water is introducedinto the flow line subsequent to the treatment with said particles todissolve particles which have agglomerated with the obstruction.

18. The method in accordance with claim 8 in which water is introducedinto the ilow line subsequent to the treatment with said particles todissolve particles which have agglomerated with the obstruction.

LEONHARD N. SCHEUERMANN. GABRIEL B. PECOT.

